Dear Arzola, A neuroendocrine tumor refers to the type of cell that the tumor grows from, not the location of the tumor. Neuroendocrine cells produce hormones or regulatory proteins, and so tumors of these cells usually have symptoms that are related to the specific hormones that they produce. You would want to have your oncologist explain to you more about this particular type of tumor as treatment would be treatment of neuroendocrine carcinoma, not the same as that for breast cancer.
Trauma to an area does not cause cancer. It may be that where the underwire of your bra was rubbing, was already effected by abnormal cells and was a sensitive area.